Wickwar Tunnel Drainage Case Study

Project Name:Wickwar Tunnel Drainage

Client: Network Rail

Duration: 24 hour blockade

Description of the contract:

Provide 2x RRV drainage lorries complete with labour, OTP operators and machine controllers

Brief Description:

To clear and establish the condition of the drainage through Wickwar tunnel.

Overview of the project

Wickwar tunnel is renowned forflooding and subsequent problems with wet beds and other water related problems. Upon a site inspection by Network rail it was found the catch pitrings were in poor condition and below the shoulder height. Some pits wereburied and the ones that were lifted showed a considerable build-up of ballastand debris inside. The water was flowing in part but was heavily restricted asthe under-ground pipe work was full and restricting the flow.

Super Rod was contacted via Network Rail to clear out the mile of drainage through and beyond Wickwar Tunnel. The aim was to find and locate the drainage catch pits andclear out the debris inside. Once the pits were clear, the drains runningbetween were high pressure water jetted and cleared. Then once complete a drainageCCTV report and footage was to be collate for an asset manager to addressfurther works.

Overview of work completed

The work faced a number of challenges, which were overcome in the following ways.

  • The access was via a removable RRAP which was manageable with the drainage machines turn table system. The allows the machines to cross the tracks at right angles, then rotate 180 degrees in line with the track saving considerable time installing a fixed RRAp system.
  • The location of the first pits were 3 miles down track towards the mouth of the tunnel. This would have caused time losses when refilling the high pressure jetting machine as it would have had to travel backwards and forwards to the access. To save time we arranged a road tanker to park near the tunnel and over pump the water directly into the machine.
  • The pits were staggered in various conditions of debris and repair. With the individual working capacity of Super Rod machines we were able to work the vactor unit and the jetting unit separately and not have to wait for one module to complete its task before starting the second module, this saving time.
  • During the 24 hour blocked we had to manage shift handovers with safety critical staff provided by Network Rail and also manage our own team of two 12 hour shifts.
  • Along the way several pits were buried under the ballast. With the use of our sonde and ezi550zi cat detector we were able to locate the pits and a team provided by Network rail exposed the pits and added extra catch pit rings ready for the machines to follow through and clean the drainage system.
  • Once clear the asset report was generated, locating all catch pits via mileage locations and a full cctv report was generated. This identified breakages, collapsed drains, cracks and other failures that could result in the system failing. Subsequently this report has been used to repair collapsed pipes and identify areas for lining.

Successes

  • Good relationships developed with Network rail staff at various levels and job descriptions and a new alliance with the water tank company supplying extra water to the machines.
  • Collaborations with all parties to deliver a successful 24 hour shift, including handovers and timesaving ideas.
  • Cost and program efficiencies were made and more were identified for future works.
  • All works completed to a high standard and all staff members returned safe without incident.

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